Fornia



Aug.7, 1928. .Y

G. N. HEIN 'ADJUSTABLE PACKING FOR HYPODERMIC SYRINGES Original FiledAug. 26, 1924 INVENTOR. @MyW/.MW M824 z/a( l A a Wwf' TToRNEYs.

40 of the Reissued ug. 7, 1928.`

y f ,UNITEDy STATES Re. 17,059 i ATENT QFFICE. n

GEORGE N. `HEIN, or'` sAN FRANCISCO, CALIEORNIA, AssrCNoR Tov NEUTYPEINSTRU- MENT COMPANY, or SAN FRANCISCO, CALIFORNIA, A CORPORATION `orCALI- FORNIA.

ADJUSTABLE PACKING POR HYPODERMIC sYRINGfEsQv origima No. 1,561,854,

`This invent-ion relates to means for adjusting the packing of piston ina. hypodermic syringe wit-hout removing the piston from within thebarrel.

The objects of the invention are, among others, to provide means wherebyan elastic piston is capable of adjustment so that a snug fit can be hadbetween the periphery of the same and the barrel wall; to provide aconstruction whereby a snugly fitting piston is adapted for readilyreleasing from the barrel wall should the same adhere or stick thereto;to provide a structure wherein the end wall of the barrel and oneportion of the packing retaining head are fashioned to afford co-actino`surfaces, the latter when in engagement reducing to a minimum therelative axial movement between the packing retaining headand the barreland wall, en-

abling the desired adjustment of the packing to be obtained on arelative rotary movement being imparted to the 'piston and barrel.

With the above mentioned and other objects in view, the inventionconsists in the j novel construction and combination of partshereinafter described, illustrated in the accompanying drawings, and setforth-in the claims hereto appended, it being understood that variouschanges in the form, proportion, size and minor details of constructionwithin the scope of the claims `may be resorted to without departingfrom the spirit or sacrificing any of the advantages of the invention.`j

. `Tol more fully comprehend the invention, reference is directed" tothe accompanying drawings,lwherein: f

Fig. l is a view partly in vertical section preferred embodiment of myconstruction' Fig. 2 is a transverse sectional View on line 2 2 of Fig.1;

Fig. 3 is a Vertical section of a barrel and syringe illustrating amodified form lof packing retaining head;

Fig. 4 is alfurtherfmodified form of retaining4 head and adjustingmechanism; e j Fig.A 5 is a st-ill further modiiiedA form,

lillustrating spring means associated with the stem of the retaininghead; and v Fig. 6 shows a sectional view of the packdated November 17,1925, lSerial No. 734,208, 4iled August 26, '19243. Application forI:reissue filed lNovember 16, 1927. Serial No. 233,696

ing member and 'relatedfparts, illustrating the position of the packingmember when the piston 1s thrust inwardly to discharge the contents ofthe syringe. l

In-the drawings, wherein like characters of reference designatecorresponding parts, 1

indicates a cylindrical piston mounted for re- Y,

ciprocation and axial rotation within a: tubular barrel 2, the samebeing a conventional hypodermic syringe barrel.` The barrel is formedwith an end wall 3 having a discharge opening L1, and in the embodimentillustrated there is detachably secured at the end 3 of the Abarrelprovided with the outlet a shell or cap 5 having a tubular dischargenozzle 6 registering with the outlet 4. The disclosure is illustratedwith the base 7 of a hypodermic needle `8 positioned on the dischargenozzle 6. One end of the piston 1 is provided with any suitable form ofringer grip 9, and the other end is domed-or rounded as at 10, andthreaded thereinto is the stem 11 of a headed packingv retaining member12, the latter being formed with a radial curved surface disposedoppositely to the dome or curved surface 10 of the piston end.

In `the embodiment illustrated in Fig. 1, the retaining head or vmember12 has extended from its outer face projections 13 which are adapted forcontact with projections 14a, and the inner surface of the end wall 3clearly illustrated in Figs. land 2, and mounted between the member 12in the domed end 10 of the piston 1, is anelastic packing or washer 14of a size, when not expanded, to lightly contact with thefinner wallsurface of the barrel 2, and the expansion of which,-due to itselasticity, being controlled by the relative adjustment of the member"12 and the end 10. vThe adjustment stated above may be accomplishedwithout withdrawing the piston from the barrel by first forcing thepiston fully within the barrel until the projections 13 engage withprojections 14, thereafter relative axial movement i inoppositedirections being imparted to the piston Iand barrel, vcausing greater orless tension to be placed on the packing; expanding and contracting thesame as desired.

Fig. '3 illustrates the outer face of the retaining member 12, being:fashioned in substantially conical formation asy at 15 to frictionallyengage corresponding surface 16 formed on the inner face of the end Wallof the barrel 2.

In the modifications illustrated in Figs. 4 and 5, the piston disclosedis of reduced diameter to that illustrated in Fig. 1, and is guided inan opening disposed centrally of a closure memberl "17 threaded to theupper end ol' the bari-cl2 as at 18.

In these respective modifications, the

headed packing retaining memberis formed.

with the beveled peripheral walls 19 and 20, and a shell guiding boss 21is disposed between the head v22 'and the threaded stem The boss 21forms a guidefor a thimble 24 loosely mounted onthestem 23 and betweenthe lower peripheral edge of which and the upper surface of theheadp22is mounted an elastic packing washer25. In Fig. 4, the upperportion ofthe thimble 23 is provided with a friction surface 26 toengage on the upward movement of the piston within the barrel 2 with thebeveled surface of the closure member 17 and transmit the resistancethrough the packing 25 to the head 22 to cause said head to vmove withthe barrel when relative axial rotation in opposite directions isimparted tothe pis-` ton and barrel.

In Fig. 5, the thimble 24 is formed with an annular seat 2-7 on whichrests the lower end of a sleeve 28 surrounding the `stem 23, andin thiscase the upper endo'f the sleeve 28 isbeveled as at 29 to provide asurface forfrictionally engaging the beveled` surface of the member 17when `the piston is drawn its full length upwardly in the barrel. Inthis construction, aspring 30 coiledabout the threaded stem 23 bearsagainst the uppcriend of the thimble 24 andnormally retains the samesnugly in contactwith the elastic packing 25.

It will be observed vthat the disclosure i1-v lustrated 'inFigs l, 2,and Bof the drawings is adjustable in the syringe only after the pistonhas completed its full discharge stroke, and the disclosure in Figs. 4and 5 enables the radjustment of the elastic pack.- ing when the pistonis ateither end of its strokeI v The position of the packing member `inactual use is illustrated-in Fig. 6. Due yto the inclined or beveledsurface 27 on the piston, the packing member will, when the pistonismoved inwardly to discharge the contents ofA the syringe, be4deflected so' as to ypresentan edged surface with minimum Contact areabetween thepacking memberY and the barrel. Such a minimum contact areawill greatly reduce the friction between the parts, and permit thesyringe to be o pT eratedwith great easeandfacility.A Fur'- thermore,this deflection of the packing` member,A will, in addition to reducingthe friction, causean expansion of theacircumferential area of thepacking member on a line a-b extending from one lower corner to theother. This expansion will cause an increased radial pressure .to beexertedupon the walls of the barrel, thereby effecting a perfect slidingseal between the packing member andthe barrel. The beveled Sur'- fa'ce27 Vaffords a seat for the 'rear `face of thepacking member when it isthus deflected, and is such as to prevent the packing member fromvbveingdeflected so far as to destroy the minimum Contact arca and increasedradial pressure.

W'here the .rear I ber is beveled, or curved as indicated at 19, asimilaraction, in the reverse direction, o'c curs tov thepacking memberwhen the piston is drawn outwardly tofill the syringe. p

Having thus described my inventiomwhat I claim and desire to-protect byLetters Patent of the United AStates is.: y f

1. A hypodermic syringe including a barface of the retainingmemrelsubstantially closed yat one. end provid-l ing a discharge port, apiston mounted for reciprocation and axial rotation therein, a packingretaining head threaded intothe end ofthe piston, said piston andretaining head being vprovide-d with opposingwalls aording'a chamberwithin which apacking is positioned said walls extending in oppor4 sitedirections outwardly from each other, an

barrel and piston 'whereby the pressuleof thepackingv against the barrelwallmayv be varied;

2. A hypodermic .syringe incl'lding abar- Vrel providedwith asubstantially closed end formedjwith recesses on its innerl surface andprovided with a discharge port, a piston mounted for reclprocation and*axial rotatlon therein, a packin retaining'head threaded into thefendoft e piston, lsaid Vpiston and retaininghead being provided'iwithcol-operating;surfacesy curved" from vthe. center ra'- diallyv inopposite directions, a relatively A' thin. elastic disc washer packing,1 positioned between the piston end andk retaining' head ywith itsperiphery, lying parallel to the'barrel surface, said* retaining head onits end provided with vprojectio'ns ,forlrecep'tion in i therecessesinithelfbarrellend wall to,A hold the same substantially"stationaryonthe imparting of, relative lrotarymovement between thebarreland pistonwhereby. the-pressure of the packing be varied.-

agains't the wall barrel 'may 105 of relative rotarywmovement betweenthe 3. A piston for hypodermic syringes includin a stem, a head carriedby one end thereo` and movable to and' from the stem end on the axialrotation ofthe stem, op-

osing surfaces of said stem end and head ing 'formed to recede outwardlyfrom each other, and an elastic packing disc disposed with its centerheld between the stem end and head wit-h its peripheral edge unsupportedand free to flex between the walls of v the stem and head and with itsperipheral surface lying at right angles to the opposite faces of thedisc.

4. A hypodermic syringe comprising a barrel, a, piston therein, anormally flat, relatively thin, square-edged, elastic `packing member onsaid piston, and a retaining member for said elastic packing member,said piston having a surface adjacent the packing member formed withbeveled corners, whereby when the piston is moved inwardly the packingmember will be deflected and present an edge contact against the barrel,minimizing thereby the friction between the packing member and barrel,and increasing the pressure of the packing member on the barrel in aradial direction.

5. A` hypodermic syringe comprising a barrel, a piston therein, anormally flat, relatively thin, square-edged, elastic packing member onthe piston, a retaining member for the elastic packing member, saidpiston and retaining member being each provided with a beveled surfaceadjacent the packing member, whereby, When the piston is moved in eitherdirection, the packing member will be deflected and present an edgecontact againstthe wall of the barrel, mlnimizing` thereby the frictionbetween the packing member on the barrel, and increasing the pressure ofthe packing member on the barrel in a radial direction.

GEORGE N. HEIN.

